Early-Onset Creutzfeldt-Jakob Disease Mimicking Immune-Mediated Encephalitis.

Objectives: The objective of this study is to explore the clinical, radiological, and pathological manifestations of a rare subtype of prion disease and their implication for differential diagnosis in case of an early onset neuropsychiatric deterioration.

Methods: We discuss a patients' clinical history, as well as the string of investigations and symptomatological evolution that finally led to a pathological diagnosis.

Results: Our patient had the extremely rare VV1 type sporadic Creutzfeldt-Jakob disease (sCJD). We explain the differential diagnosis of progressive encephalomyelitis with rigidity and myoclonus and its implications for treatment.

Conclusion: sCJD, especially the VV1 subtype, can present at an early age with an insidious psychiatric onset. Classical findings of prion disease-14-3-3 protein, PSWC on electroencephalography, and magnetic resonance imaging patterns-are not always present. The presence of neural autoantibodies does not always implicate pathogenicity in the presence of other neurological/neurodegenerative conditions.